1. Field of the Invention
This invention relates generally to the field of automatic call distribution systems.
2. Description of the Prior Art
Automatic call distribution systems employing a multiport switch controlled by a central processing unit for selectively interconnecting a plurality of external telephonic units of an external telephonic network with internal telephonic units of the call distribution system are well known. Examples of such call distributor systems are shown in U.S. Pat. No. 5,268,903 of Jones et al. entitled "Multichannel Telephonic Switching Network With Different Signaling Formats and Cross Connect/PBX Treatment Selectable For Each Channel", issued Dec. 7, 1993; U.S. Pat. No. 5,140,611 of Jones et al. entitled "Pulse Width Modulated Self-Clocking and Self-Synchronizing Data Transmission and Method for a Telephonic Communication Network Switching System", issued Aug. 18, 1992 and U.S. Pat. No. 5,127,004 of Lenihan et al. entitled "Tone and Announcement Message Code Generator for a Telephonic Switching System and Method", issued Jun. 30, 1992.
However, it has not been known in such automatic call distribution systems to employ standardized internal telephonic units, such as Integrated Services Digital Network based, or ISDN, telephonic units. Instead, such systems have employed special telephonic units especially adapted for automatic call distribution systems. Integrated Services Digital Network (ISDN) is a telephony service which connects telephone users digitally to ISDN based telephone switching equipment.
Integrated Services Digital Network provides for a signal service that supports many forms of signal traffic on a single platform. ISDN offers standardized interfaces that support speech, low-speed and high-speed data and video traffic carried on a digital signaling system. The international standards for ISDN based telephonic equipment originated by the Comite Consultatif Internationale de Telegraphique et Telephonique (International Telegraph and Telephone Consultive Committee) or CCITT. CCITT is an agency of the International Telecommunication Union (ITU), which is an agency of the UN. The CCITT provides worldwide coordination for telephone and data communications systems. The technical recommendations of the CCITT regarding ISDN have become internationally recognized standards. The ISDN standards originated from the CCITT have been adapted to meet the needs of various telephonic companies such as American Telephone and Telegraph, Northern Telecom, NEC, Fujitsu, and Telrad.
This standard service provides ISDN users the flexibility to purchase ISDN hardware from other manufacturers to use in an ISDN telephonic system. From a design standpoint, ISDN offers standardized ISDN based integrated circuits for implementation in telephonic units. The compactness of these integrated circuits saves valuable space in the electronics packaging for the telephonic unit housing. Users not implementing ISDN based equipment must develop their own equipment which is designed to meet the needs of to each individual user.
ISDN Basic Rate Interface (BRI) is a service which directly connects to a ISDN telephonic unit of a user. The telephone equipment used communicates both digital information about the call as well as voice information over two twisted wiring pairs, one pair for receive and one pair for transmit to the telephone switching equipment. The information is formatted according to international standards as a series of three channels on each ISDN BRI line. There are two bearer B-channels at 64 kbs and one signalling D-channel at 16 kbs in the basic rate line. A B-channel is either voice or data from the user. The D-channel is used to communicate call control messages between the telephonic unit and the switching equipment. The physical type of BRI line used with on-premise switching equipment is called an S interface. The standards for the S-interface provide for up to eight telephones for connection to a twisted wiring pair.
ISDN software and hardware are informally referred to and divided into three logical layers. Layer 1 is the physical layer and provides the standard to physically interconnect telephonic equipment of different ISDN vendors. Clock synchronization, line powering, and even the physical connectors used are specified at this layer. Layer 2 is known as the data layer and provides a software interface into layer 1. Layer 2 also handles the transmission of data between telephone equipment and a telephonic switching system and management of all message error detection and correction. If an error occurs during transmission of data between the switch and the phone, layer 2 may reattempt sending the message or may notify the next layer, layer 3, that the transmission of data was unsuccessful. Layer 3 is the application layer, and it is here where call control messages are generated and interpreted. For example, messages are sent by a telephonic unit in layer 3 to specify a telephone key press by a user, or by the telephone switching equipment, to put alphanumeric characters into a liquid crystal display of the telephonic unit.
Standard ISDN layer 3 protocols provided by companies such as AT&T and Northern Telecom, address the requirements of the Private Branch Exchange (PBX) market, but lack essential requirements for automatic call distribution systems. These requirements include minimal call setup time, selective telephonic ringing, selective elimination of the requirement of lifting a handset off-hook to answer an incoming call, simplified conference call control, avoidance of call connection to unattended operator units and general minimization of the number of key actuations needed to perform frequently performed operations.
Because the standard ISDN protocols lack such functionality, the resultant inefficiency resulting from use of ISDN telephone in an automatic call distributor (ACD) environment has precluded their effective use in such applications. But for the lack of functionality, the economics of scale, standardization and other advantages of using ISDN telephones could be obtained.
The ACD environment requires that operators stationed at telephonic units be utilized in a time efficient manner in servicing telephone calls, while standard ISDN protocol incompatibility requires numerous sets of data messages to be sent between a multiport switch and a telephonic unit in order to answer a telephone call. An ACD environment requires the quick answering of calls at an internal telephonic unit given the high volume of calls presented to agents servicing the calls at the telephonic units. The speed to answer a telephonic call significantly effects the number of calls which are answered during a day. Disadvantageously, standard ISDN protocol requires that telephonic calls to be answered through use of a switchhook of the telephonic unit to change state in order for a telephonic call to be sent to the telephonic unit.
In an automatic call distribution environment, such as in the telemarketing industry, thousands of calls from a single user are taken daily. Since 1-800, or toll free, calls charge the receiver of the call for the period a call is handled, the extra amount of time required to lift a telephone handset from a switchhook for each and every call becomes prohibitively expensive over time. A problem exists with standard ISDN telephonic units, since they require the use of a switchhook or some other external signaling means for a telephonic unit to accept an incoming call. It is imperative in an ACD environment to reduce the amount of time an operator or agent spends to service a call in order to permit more calls to be taken over a period of time. Thus, a need is created which allows incoming callers to be immediately connected to an operator of an ISDN based telephonic device when the operator is not active on another call.
Known ISDN based telephonic units do not meet the special requirements for an automatic call distribution environment, since such units unacceptably enable operators at any time to enter into a telephonic unit customizing mode. This creates a security problem, since telephonic unit default settings are changeable, such as different types of ringing, loudness of the ring, etc. Moreover, in an ACD environment, thousands of calls are serviced daily, and operators or agents are tempted to enter into the telephonic unit customizing mode in which no calls can be placed to their unit in order to take unauthorized work breaks. This problem increases the amount of unauthorized break time by unproductive operators and consequently permits fewer calls to be taken over a period of time.
Agents or operators in an ACD environment must use the communication devices for communicating through the telephonic unit. It is therefore important that the telephonic unit detect when audio communication devices, headsets or handsets, are not plugged into the unit so that the automatic call distributor does not transfer calls to a telephonic unit where the agent has unplugged their headset or handset and has left the unit unattended. Disadvantageously, known ISDN telephonic units do not provide a means for detecting the removal of a communication device from a unit and therefore cannot be caused to automatically preclude distribution of calls to an unattended telephonic unit.
Known ISDN based telephonic units require the unit to audibly ring in order to indicate a call to an operator. Disadvantageously, in an ACD environment, audible ringing in a single room fitted with a multitude of ISDN telephonic units creates a noisy and distracting work environment for the ACD operators. However, under certain circumstances, such as when an operator is across a room from a telephonic unit, it may be desirable to have the telephonic unit ring. Additionally, it is also desirable that a ringing element be activated when an operator is servicing a connected call on another line. Ringing at a telephonic unit is also useful to alert an operator when the ACD system is writing an important message to a liquid crystal message display on the unit. It is also beneficial for the system to alert an operator as to the arrival of a display message when a call is not present. Standard ISDN telephonic units do not allow selective ringing of the telephone unit, but rather ring always and only upon, the initial arrival of an incoming call.
Known ISDN based systems allow for the creation of calls between multiple parties, typically referred to as conference calls. These calls are controlled by only one operator (primary operator) who generates call connections. It is desirable to allow a secondary operator (such as a supervisor) of a primary operator the ability to automatically be joined into an existing conversation while the primary operator is actively conversing on a call. However, in these ISDN systems these calls do not meet the special requirements for an automatic call distributor environment, since the known ISDN based telephonic units cannot connect a secondary operator to an existing conversation automatically as a result of actions taken by the secondary operators.
Other desirable conference calling features are inachievable with the use of an ISDN telephone, such as the ability to place one of the conferencing parties on hold while continuing the conference between the remaining parties and then selectively removing them from hold, and for indicating, or acknowledging, when parties have joined the conference and to selectively drop parties from the conference with the actuation of a single key.